we are not alone: other planets, other...
TRANSCRIPT
Edmund Bertschinger
MIT Department of Physics andKavli Institute for Astrophysics and
Space Research
We are not alone: Other planets, other earths?
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Earth and Mars – or Mars and Earth?
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Life on Mars?
R. Villard, STScI
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Martian Meteorite found in Antarctica
McKay et al. 1996: carbonate globules – evidence for microbial life? Probably not.
Lunar and Planetary Institute
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Mars Global Surveyor: fresh water?
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Family Portrait: 4 rocky planets, 2 gas giants, 2 ice giants
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Planets around other stars: exoplanetsAs of December, 2006:
209 planets183 Doppler shift
4 microlensing14 transits
4 imaging4 pulsar timing
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As of July 22, 2008
307 confirmed planets
Detected by Doppler shifts: 290249 planetary systems (29 multiple planet systems)
Transiting planets (found initially by Doppler): 52Detected by microlensing: 7Detected by imaging: 5Detected by timing: 3 systems containing 5 planets
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How to find other planetary systems
Doppler measurement of stellar wobble: planets’ gravity pulls on star
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Figure from California-Carnegie Planet SearchFirst success: 1995, Mayor and Queloz
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How to find other planetary systems
Transit: planet passes in front of star, dims the light a tiny amount
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Both the Doppler and Transit methods can much more easily find close-in, Jupiter mass planets
than earth-like planets
Space Telescope Science Institute
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How to find other planetary systems
Gravitational Microlensing
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The gravity of a planet orbiting a star causes
light rays to bend, changing the amount of light reaching the
earth.
Background star
Enhanced image at
earth
25 January 2006: the star OGLE-2005-BLG-390L has a planet of mass about 10 earth masses, in a 10-year orbit!
(very similar to Neptune)
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How to find other planetary systems
Direct imaging
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Family Comparison
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Family Comparison
R. Villard, STScI
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What have we learned?
Jupiter
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Jupiter
What have we learned?
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What have we learned?
Mercury
Hot Jupiters
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What have we learned?
Stars with more heavy
elements are more likely to
host planets
(California -Carnegie
Planet Search)
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What have we learned?
Some planets likely
have right conditions for liquid
water(it’s 300K in here!)
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J.F. Kasting et al.
Habitable zone for life
Darren Williams, Penn State Erie
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J.F. Kasting et al.
Extrasolar planets
Habitable zone for life
Darren Williams, Penn State Erie
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Future: search for earthlike planets and life
Search method: transits using satelliteESA Corot mission launched 2007.NASA Kepler: 2/2009 launch scheduledMIT/Harvard TESS: proposed wide-field survey mission.
Terrestrial Planet Finder: 2015 or later
Atmospheric Spectroscopy
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Additional Credits and InformationCredits:
Prof. Josh Winn, MITWater on Mars: antwrp.gsfc.nasa.gov/apod/ - Astronomy
Picture of the DaySahara Desert and Mars: Lunar and Planetary InstituteBlack hole embedding diagram: Scott Hughes, MITFigures showing Mean Orbital Distance created online at
http://extrasolar.net/charts.aspKepler and TPF: NASA/Jet Propulsion Laboratory
Books:Origins: Fourteen Billion Years of Cosmic Evolution, Neil
deGrasse Tyson and Donald GoldsmithEarth: An Intimate History, Richard ForteyThe Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution,
Richard Dawkins
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Websites for more information
www.alma.info – ALMA gateway
Extrasolar.net – General information about exoplanets
Exoplanets.org – California-Carnegie exoplanet searches
www.astrobio.net - Astrobiology
Solstation.com – General astronomy information, sky maps
antwrp.gsfc.nasa.gov/apod/ - Astronomy Picture of the Day